1. Field of the Invention
The present invention relates to a magnetic head polishing device for polishing an object to be polished where a plurality of magnetic heads are disposed and a magnetic head polishing method, and more particularly to a device for correcting a bend of the workpiece or object to be polished at the time of polishing.
2. Related Background Art
A thin film magnetic head used in a magnetic disk device or the like is made up of parts obtained by machining a bar-shaped ceramics (hereinafter referred to xe2x80x9cceramic barxe2x80x9d) where a large number of element parts made of magnetic thin films and the like, which form an induced magnetic conversion element or a magnetic resistor element (hereinafter referred to as xe2x80x9cMR elementxe2x80x9d) and the like, are formed on a surface in a line. The large number of element parts are formed on a wafer-shaped ceramic substrate at the same time, and the ceramic substrate is cut into a bar shape in one direction, to thereby obtain the above-mentioned ceramic bar.
The large number of element parts are formed on the wafer-shaped ceramic substrate at the same time with the use of a thin film forming and processing technique represented by a semiconductor manufacturing technique. In this process, the respective thin films for magnetic resistance measurement, a magnetic pole, a coil, insulation, and the like, are subjected to film formation, photoresist coating, exposure of a wiring shape, and the like, the removal of the photoresist on a portion to be exposed, a film etching on the portion to be exposed, the removable of the photoresist on an exposing portion, and the like. Thereafter, a protective film is formed on the uppermost portion, and a process of forming the element portion is completed.
In addition, in the next process, a ceramic bar formed with a plurality of element parts is subjected to a polishing process that machines a throat height, an MR height, or the like of each element part to an appropriate value, and other processes. In general, in the magnetic disk device, in order to stabilize the output characteristic from the magnetic head, it is necessary to keep a distance between the magnetic pole portion of the magnetic head and a recording medium surface to a very narrow constant distance. The throat height or the MR height becomes an important parameter that regulates this distance.
In a subsequent process, the ceramic bar is separated into the respective element parts, individually, and the respective element parts constitute one part of the magnetic head for the magnetic disk device. When the magnetic head is used for the magnetic disk device, the ceramic portion becomes a slider that floats due to an air pressure by the rotation of a disk on the magnetic disk, and the element portion becomes a head core that conducts the record and/or reproduction of a magnetic signal of the disk.
The throw height is regulated by a magnetic pole leading portion that conducts the record and reproduction of a magnetic signal in the above head core, and is directed to the length (height) of a portion of two magnetic poles that face each other with a fine gap therebetween. The MR height is directed to the length (height) from an end portion on the side of the surface facing the medium of the MR element to the opposite end portion. In order to enable an appropriate recording and reproduction of the signal, it is needed that the values of the throat height and the MR height are set to given values, and a high precision is required for polishing process in order to obtain the given values.
However, in general, the above ceramic bar has a distortion, a bend or the like due to a stress caused by cutting of the respective element portions from the ceramic substrate or the formation of the element portions, and the like, and it is difficult to obtain the above-mentioned high processing accuracy only by fixing the ceramic bar to conduct the polishing process. For that reason, there has been proposed a device for polishing the magnetic head in the form of a ceramic bar with a high precision as disclosed, for example, in U.S. Pat. No. 5,620,356, instead of the general polishing device. Also, the present applicants have proposed such devices and methods (Japanese Patent Application No. 11-162799, and the like).
A method of polishing the above ceramic bar in fact will be described below.
First, a counter surface to the polished surface of the ceramic bar is stuck on a jig by means of an adhesive or the like, and the surface to be polished of the ceramic bar is pushed toward a polishing surface of a polishing bed or base through the jig, to thereby polish the surface to be polished. The jig is of a beam structure, and a load is given to specific points three to seven on the jig from the outside of the jig, to thereby deform the jig per se. In addition, the beam structure facilitates a portion to which the ceramic bar is stuck to be complicatedly deformed by the above load and also can correct the bend or the like of the ceramic per se by bending the stuck ceramic bar at the same time.
During polishing, the value of the throat height or the like is optically or electrically measured on a given element portion on the ceramic bar fixed by the jig, and a difference between the measured value and a desired value, that is, a polishing amount required at the time of measurement is obtained. The loads at a plurality of points are adjusted on the basis of the required polishing amount at an obtained predetermined element portion and a portion close to the element portion, and a process of conducting polishing while deforming the ceramic bar through the jig is repeated, to thereby fall values of the throat height or the like of all the elements formed in the ceramic bar within a given range.
In the above process, the jig is made into a beam structure in order to make the deformation easy, and an opening portion into which a pin or the like that gives a load is inserted is defined in the beam portion. A load caused by an actuator such as a low frictional cylinder is transmitted to the pin through a transmission part, to thereby deform the entire jig and deform the ceramic bar fixed to a part of the jig, or adjust a load on the respective ceramic bar portions. A specific example of the jig that conducts the effective deformation or the load diffusion on the ceramic bar is disclosed in Japanese Patent Application No. 10-178949 made by the present applicants.
However, as the recording density of the magnetic recording medium is made high, an error range which is allowed to the value of the throat height or the like during the polishing process becomes narrower. In order to comply with this requirement in the above conventional device, it is necessary to give a fine deformation by a ceramic bar holding portion. However, in order to obtain the fine deformation, more points to which the load is applied are disposed, and a device that can give larger loads to those points is required. Taking the size of the actuator having a required stroke, and the like, into consideration, it is difficult to structure an actual device. Also, the jig of the conventional device in which the entire jig is always deformed is naturally improper in deforming the respective parts, independently.
For that reason, the present applicant has proposed a method in which a main load that presses the ceramic bar against the polishing surface is given by about one to three actuators, and pressing forces from a plurality of micro-actuators small in stroke are directly effected on the portion that holds the ceramic bar for fine adjustment. According to this method, the micro-actuator small in stroke, and the like, can be employed by directly effecting the pressing force onto the ceramic bar holding portion, and a problem on a space to which the actuator is attached is eliminated. In addition, a specific portion of the ceramic bar holding portion can be pressed, thereby being capable of more finely correcting the bend of the ceramic bar.
As described above, an error allowed to the machining of the throw height or the like becomes smaller with time, and at present, a precision of, for example, xc2x10.01 xcexcm or less is required within the ceramic bar. The polishing is conducted while the bend of the ceramic bar, or the like, is corrected, for example, by using the above method proposed by the present applicant, thereby being capable of obtaining the above precision. However, the element which has been actually formed in a ceramic bar shape has an error in the formation position caused in the element forming process at the same time. For example, in the case of exposing the photoresist, there is a case where an exposure process is not conducted on all the portions on the wafer at the same time, but an upper surface of the wafer is divided into a plurality of portions, and the exposure process is conducted on the respective portions. In general, there has been known that the positioning at the time of exposure by an exposing device has an error of 0.01 to 0.05 xcexcm.
Similarly, when being viewed in a longitudinal direction, the element on one ceramic bar is subjected to an exposure process where the element is divided into a plurality of portions. The positional displacement of the element caused by this exposure process may largely exceed the above requested precision in degree depending on the displacement direction, and the positional displacement needs to be corrected in addition to the correction to the bend of the above ceramic bar.
In addition, in the above element forming process, processes such as the film formation, the exposure and the etching are conducted with respect to a plurality of thin films, and errors in the thickness direction of the thin film, in the width direction of a wiring and in the longitudinal direction of the wiring are caused in the respective processes. Those errors are caused within a region which is exposed at one time, and all of those errors are superimposed on each other and detected as positional errors between the respective elements in the polishing direction and as a difference of the required polishing amount for each of the elements in adjusting the throat height or the like.
In the case where an attempt is made to eliminate the respective factors that cause those errors, it is considered that the machining allowable values allowed in the respective processes are made as small as possible. However, in the case where the machining allowable values are made small, there are presumed demerits such as the deterioration of the yield caused by producing the elements out of the allowable range, and an increase in the machining period of time for enhancing the exposure precision, which is not practical. Also, it is proposed that attention is paid to only the positional displacement in the exposure process, and only a region which is exposed at one time is divided and machined. However, similarly, this process leads to an increase in the costs which are required for the machining device or a reduction of productivity of the machining device and therefore is not practical.
The present invention has been made under the above circumstances, and therefore an object of the present invention is to provide a device which can give a complicated bent deformation to an object to be polished such as a ceramic bar in accordance with the positional displacements of respective elements which are caused by an exposure processing or the like, whereby the amount of polishing the object to be polished is adjusted to unify the non-polished portion of the respective elements in a process of polishing the object to be polished.
In order to solve the above problem, according to the present invention, there is provided a polishing device for polishing an object to be polished which is elongated in one direction, in which a plane of the object to be polished extending in the longitudinal direction is divided into a plurality of regions, and a plurality of elements each consisting of at least one of an electromagnetic conversion element and a magnetroelectric conversion element are formed in the longitudinal direction in each of the divided regions, the polishing device comprising a polishing bed having a polishing surface which is rotationally driven, a polishing head mounted frame movably disposed on the polishing surface, and a polishing head supported by the polishing head mounted frame, characterized in that the polishing head includes a jig that has a holding portion that extends in a longitudinal direction and holds the object to be polished at a given position of the holding portion, a support portion that supports the jig, an elevating portion that is integrated with the support portion and elevates with respect to the polishing surface, and a plurality of holding portion deforming means that give a load which deforms the holding portion and the object to be polished to the holding portion, and that the holding portion deforming means are disposed so as not to give the load on boundaries between the plurality of regions.
The division of the plane of the object to be polished which extends in the longitudinal direction into the plurality of regions is caused, for example, by conducting the above-mentioned division exposure. Also, the holding portion deforming means may be disposed on the jig or may be disposed independently from the jig.
Also, in order to solve the above problem, according to the present invention, there is provided a polishing device for polishing an object to be polished which is elongated in one direction, in which a plurality of elements each consisting of at least one of an electromagnetic conversion element and a magnetroelectric conversion element are formed in the longitudinal direction on a plane that extends in the longitudinal direction, the polishing device comprising a polishing bed having a polishing surface which is rotationally driven, a polishing head mounted frame movably disposed on the polishing surface and a polishing head supported by the polishing head mounted frame, characterized in that the polishing head includes a jig that has a holding portion that extends in a longitudinal direction and holds the object to be polished at a given position of the holding portion, a support portion that supports the jig, an elevating portion that is integrated with the support portion and elevates with respect to the polishing surface, and a plurality of holding portion deforming means that give a load which deforms the holding portion and the object to be polished to the holding portion, and that the holding portion deforming means are disposed so as to give the load to the plurality of elements, independently.
Also, the holding portion deforming means may be disposed on the jig or may be disposed independently from the jig. In addition, it may be that the polishing head includes an actuator, the jig has a through-hole disposed in a direction perpendicular to a direction along which the holding portion deforming means gives the load in the center of the longitudinal direction, the jig is supported on the support portion by a support pin that penetrates the through-hole, and the actuator effects a force that pushes or pulls up the jig in a direction perpendicular to the polishing surface through the support pin.
Further, it may be that the polishing head has a correcting actuator, and the support portion has a positioning pin, the jig has a recess disposed in a direction perpendicular to the direction along which the holding portion deforming means gives the load on both of ends in the longitudinal direction, the jig is positioned by the positioning pin inserted into the recess, and the correcting actuator adjusts a press force with respect to the polishing surface of the jig through the positioning pin. In addition, the polishing head may have an adjust ring elastically supported by the polishing head mounted frame, and the adjust ring is in contact with the polishing surface while being elastically supported by the polishing head mounting frame so that an angle facing the polishing surface may be regulated by the adjust ring.
Still further, the polishing head may be rotatably attached on the polishing head mounting rail. Also, the polishing device may have a polishing head swinging means, and the polishing head swinging means may allow the polishing head to conduct the reciprocatingly rotating motion within a given angle range. In addition, the polishing device may include a means for detecting the required polishing amount of the object to be polished and a drive means for driving the plurality of holding portion deforming means on the basis of the detected required polishing amount. Also, the object to be polished may be made of bar-shaped ceramic where a plurality of magnetic heads are formed.
Yet still further, in order to solve the above problem, according to the present invention, there is provided a polishing method of an object to be polished which is elongated in one direction, in which a plane of the object to be polished extending in the longitudinal direction is divided into a plurality of regions, and a plurality of elements each consisting of at least one of an electromagnetic conversion element and a magnetroelectric conversion element are formed in the longitudinal direction in each of the divided regions, the polishing method comprising, a step of holding the object to be polished by the jig, substantially uniformly pressing the object to be polished, toward the polishing surface formed on the polishing bed rotatably driven, through the jig in the longitudinal direction, and polishing the object to be polished, characterized in that when the object to be polished is substantially uniformly pressed toward the polishing surface, a load for adjusting the deformation amount in the periphery of the load applied points of the object to be polished in a plurality of load applied points in the longitudinal direction is given to the object to be polished in addition to the substantially uniform press, and the load applied points are disposed other than the boundary portions of the plurality of divided regions. Also, it is preferable that the load applied points are close to the boundary portions and disposed at both sides thereof.
Yet still further, in order to solve the above problem, according to the present invention, there is provided a polishing method for polishing an object to be polished which is longitudinal in one direction, in which a plurality of elements each consisting of at least one of an electromagnetic conversion element and a magnetroelectric conversion element are formed in the longitudinal direction on a plane that extends in the longitudinal direction, the polishing method comprising, a step of holding the object to be polished by the jig, substantially uniformly pressing the object to be polished, toward the polishing surface formed on the polishing bed rotatably driven, through the jig in the longitudinal direction, and polishing the object to be polished, characterized in that when the object to be polished is substantially uniformly pressed toward the polishing surface, a load for adjusting the deformation amount of the portion on which the plurality of elements of the object to be polished are formed, respectively, is given to the plurality of elements, independently, in addition to the substantially uniform press. Also, it is preferable that the load is given to the plurality of elements except for the center portion between the respective elements.